It is a fact that most injuries which demand immobilization for emergency transport and recuperation would benefit from the superior fit and support of a cast. Unfortunately, casts suffer several restrictive drawbacks. Casts:
are awkward and time consuming to apply PA1 are bulky and cumbersome PA1 offer no adjustability PA1 must be destroyed when removed PA1 offer poor ventilation
These drawbacks incite the need for alternative immobilization devices that overcome these deficiencies. Splints are examples of immobilization devices that sacrifice both fit and support yet solve most of casts inherent drawbacks. Splints are easy to apply, adjust, remove and provide ventilation. It is this versatility that justifies their use in many medical situations.
Numerous techniques and methods have been proposed which address the need for immobilization devices that combine the advantages of both the splint and cast. Hill-Byrne, U.S. Pat. No. 4,727,865 describes a method that allows a cast to be removed. The method consists of fabricating a cast in the traditional manner, cutting the cast into two sections, attaching fasteners to their common interface and lastly assembling the unit on the injury. Hollrah U.S. Pat. No. 4,766,890, describes a cast with an underlying support structure of spaced apart ribs. These ribs from a grid that keep the cast from contacting the injury. While the former allows the cast to be removed and the latter improves ventilation, both of these methods increase the time and complexity of the casting process, thus prohibiting their use in numerous medical situations.
Larson, U.S. Pat. No. 3,580,248 describes a rigid cast-like structure that uses an inflatable liner to provide adjustability and hinges to provide ease of removal. However, the complexity of the fabrication demands that the apparatus be manufactured prior to the injury. This necessitates the injury to be immobilized in the casts predetermined orientation. This drastically lessons the methods' versatility.
Sterling, U.S. Pat. No. 4,019,504 describes a splint that is adjustable. The apparatus consists of two slats connected by a slidable pivot. Santy, U.S. Pat. No. 4,280,490 provides numerous hinges to allow the structure to be adjusted in three planes. These devices do constitute an improvement over previous splinting apparatuses, however, they still offer limited fit and immobilization.
In order to attain a high degree of fit, comfort and immobilization the apparatus must do more than adjust, it must be formable. Further, if it is to remain versatile, it must be reformable. Numerous devices have been proposed which offer reformable structures. One method present in the art is to use a malleable material to provide reformability. U.S. Pat. No. 2,506,464 pivotaly connects two strips of metal to provide four bendable legs for splinting a finger. Sheinberg, U.S. Pat. No. 3,955,565 describes a flat u-shaped strip of malleable metal that is used to sandwich injured limbs. These devices can, to some extent, be bent to fit a patient. Unfortunately, they require extensive handling and adjustment, while providing only minimal conformability. Further, the force these devices can resist cannot be greater than the force that formed them. In many instances, this force is not sufficient to offer adequate rigidity.
It would be desirable to have an immobilization device that is easily conformable yet structurally rigid. These conflicting requirements impel the need for a structure that has two states, conformable and rigid. Several structures have been proposed that offer this dual-state characteristic. Seeler, U.S. Pat. No. 4,508,112 describes a fluid pressure actuated immobilizing structure. The device consists of two flexible and coaxial tubes. The inner tube expands under fluid pressure and exerts a force on the outer tube which rigidizes the structure. Unfortunately, this device is awkward to apply, is excessively bulky and requires a pressure source. Wirtz, U.S. Pat. No. 4,657,003 describes an immobilizing device that consists of polystyrene beads contained in an evacuable plastic bag. After the bag is placed around the injury, a vacuum source is used to evacuate the bag. This causes the beads to compress. The frictional force created allows the device to form a semi-rigid structure. Since the maximum pressure available to compact these beads is only atmospheric, these devices cannot be used when significant structural support is needed. Also, this device is necessarily bulky.
Materials such as those described in U.S. Pat. Nos. 4,483,333 and 4,600,618 are a type of material that are used extensively to provide a dual-state structure. These low temperature thermoforming plastic materials are reformable at raised temperatures below their curing point and are structurally rigid at normal ambient temperature. Their most restrictive drawback is that an external heating source must be readily available. Another problem is the time and complexity needed to fabricate such a device. Groiso, U.S. Pat. No. 4,852,556 addresses these problems by offering a pre-made support structure that is stored in a sterilized bag filled with water. Though Groiso was successful at minimizing the time and complexity of fabrication, a heating source must be available to heat the hot water. Since hot water is the preferred heating means, readjustment of the structure entails removal of the apparatus from the injury, in order to reheat the thermo plastic material. Further, since the apparatus must be removed when it is structurally rigid, it cannot encircle the injury. This limits its immobilization and rigidity.
The patents cited above all offer solutions to particular insufficiencies inherent to immobilization and support structures. Some have solved one problem by creating another. While others have attained varying degrees of success in providing a versatile immobilizing/support device.
It is a principle objective of the invention to describe a general support structure that can be used in any situation that requires structural support and reformability.
A second objective of the present invention is to provide a dual-state support structure that could be used to provide superior immobilization and versatility for supporting portions of the human body with no significant drawbacks.